a suffix of nouns, often corresponding to verbs ending in -ize or nouns ending in -ism, that denote a person who practices or is concerned with something, or holds certain principles, doctrines, etc.: apologist; dramatist; machinist; novelist; realist; socialist; Thomist.
countable] a distinctive belief, theory, system, or practice; anything that could be referred to by a word with the suffix -ism:capitalism, socialism, and other isms.
